have been reported . these are typically referred to as retro @ - @ na ##zar ##ov cy ##cl ##ization reactions . nitrogen analogue ##s of the na ##zar ##ov cy ##cl ##ization reaction ( known as im ##ino @ - @ na ##zar ##ov cy ##cl ##ization reactions ) have few instances ; there is one example of a generalized im ##ino @ - @ na ##zar ##ov cy ##cl ##ization reported ( shown below ) , and several iso @ - @ im ##ino @ - @ na ##zar ##ov reactions in the literature . even these tend to suffer from poor stereo ##sel ##ect ##ivity , poor yields , or narrow scope . the difficulty stems from the relative over @ - @ stabilization of
have been reported. these are typically referred to as retro @ - @ nazarov cyclization reactions. nitrogen analogues of the nazarov cyclization reaction ( known as imino @ - @ nazarov cyclization reactions ) have few instances ; there is one example of a generalized imino @ - @ nazarov cyclization reported ( shown below ), and several iso @ - @ imino @ - @ nazarov reactions in the literature. even these tend to suffer from poor stereoselectivity, poor yields, or narrow scope. the difficulty stems from the relative over @ - @ stabilization of